const express = require("express");
const router = express.Router();

const { Category, Course } = require("../../models");
const { Op } = require("sequelize");
const { NotFoundError } = require('../../utils/errors');
const { success, failure } = require('../../utils/responses');

//查询所有分类
router.get("/", async function (req, res) {
  try {
    const query = req.query;

    //当前第几页
    const currentPage = Math.abs(Number(query.currentPage)) || 1;

    //每页多少条数据
    const pageSize = Math.abs(Number(query.pageSize)) || 10;

    const offset = (currentPage - 1) * pageSize;

    const condition = {
      order: [['rank', 'ASC'], ['id', 'ASC']],
      limit: pageSize,
      offset: offset,
    };
    if (query.name) {
      condition.where = {
        name: {
          [Op.like]: `%${query.name}%`,
        },
      };
    }

    const { count, rows } = await Category.findAndCountAll(condition);
    success(res, "查询分类列表成功", {
      categorys: rows,
      pagination: {
        total: count,
        currentPage,
        pageSize,
      },
    });
  } catch (error) {
    failure(res, error);
  }
});

//查询分类详情
router.get("/:id", async function (req, res) {
  try {
    const category = await getCategory(req);

    success(res, "查询分类成功", { category });
  } catch (error) {
    failure(res, error);
  }
});

//创建分类
router.post("/", async function (req, res) {
  try {
    //白名单过滤
    const body = filterBody(req);
    const category = await Category.create(body);

    success(res, "创建分类成功", { category }, 201);
  } catch (error) {
    failure(res, error);
  }
});

//删除分类
router.delete('/:id', async function (req, res) {
  try {
    const category = await getCategory(req);

    const count = await Course.count({ where: { categoryId: req.params.id } });
    if (count > 0) {
      throw new Error('当前分类有课程，无法删除。');
    }

    await category.destroy();
    success(res, '删除分类成功。');
  } catch (error) {
    failure(res, error);
  }
});

//更新分类
router.put("/:id", async function (req, res) {
  try {
    const category = await getCategory(req);

    //白名单过滤
    const body = filterBody(req);

    await category.update(body);

    success(res, "更新分类成功", { category });
  } catch (error) {
    failure(res, error);
  }
});

/**
 * 公共方法：查询当前分类
 */
async function getCategory(req) {
  const { id } = req.params;

  const category = await Category.findByPk(id);

  if (!category) {
    throw new NotFoundError(`ID:${id}的分类未找到`);
  }
  return category;
}

function filterBody(req) {
  return {
    name: req.body.name,
    rank: req.body.rank,
  };
}

module.exports = router;
